1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Filesystem parameter parser.
3 *
4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/export.h>
9#include <linux/fs_context.h>
10#include <linux/fs_parser.h>
11#include <linux/slab.h>
12#include <linux/security.h>
13#include <linux/namei.h>
14#include "internal.h"
15
16const struct constant_table bool_names[] = {
17 { "0", false },
18 { .name: "1", .value: true },
19 { .name: "false", .value: false },
20 { .name: "no", .value: false },
21 { .name: "true", .value: true },
22 { .name: "yes", .value: true },
23 { },
24};
25EXPORT_SYMBOL(bool_names);
26
27static const struct constant_table *
28__lookup_constant(const struct constant_table *tbl, const char *name)
29{
30 for ( ; tbl->name; tbl++)
31 if (strcmp(name, tbl->name) == 0)
32 return tbl;
33 return NULL;
34}
35
36/**
37 * lookup_constant - Look up a constant by name in an ordered table
38 * @tbl: The table of constants to search.
39 * @name: The name to look up.
40 * @not_found: The value to return if the name is not found.
41 */
42int lookup_constant(const struct constant_table *tbl, const char *name, int not_found)
43{
44 const struct constant_table *p = __lookup_constant(tbl, name);
45
46 return p ? p->value : not_found;
47}
48EXPORT_SYMBOL(lookup_constant);
49
50static inline bool is_flag(const struct fs_parameter_spec *p)
51{
52 return p->type == NULL;
53}
54
55static const struct fs_parameter_spec *fs_lookup_key(
56 const struct fs_parameter_spec *desc,
57 struct fs_parameter *param, bool *negated)
58{
59 const struct fs_parameter_spec *p, *other = NULL;
60 const char *name = param->key;
61 bool want_flag = param->type == fs_value_is_flag;
62
63 *negated = false;
64 for (p = desc; p->name; p++) {
65 if (strcmp(p->name, name) != 0)
66 continue;
67 if (likely(is_flag(p) == want_flag))
68 return p;
69 other = p;
70 }
71 if (want_flag) {
72 if (name[0] == 'n' && name[1] == 'o' && name[2]) {
73 for (p = desc; p->name; p++) {
74 if (strcmp(p->name, name + 2) != 0)
75 continue;
76 if (!(p->flags & fs_param_neg_with_no))
77 continue;
78 *negated = true;
79 return p;
80 }
81 }
82 }
83 return other;
84}
85
86/*
87 * __fs_parse - Parse a filesystem configuration parameter
88 * @log: The filesystem context to log errors through.
89 * @desc: The parameter description to use.
90 * @param: The parameter.
91 * @result: Where to place the result of the parse
92 *
93 * Parse a filesystem configuration parameter and attempt a conversion for a
94 * simple parameter for which this is requested. If successful, the determined
95 * parameter ID is placed into @result->key, the desired type is indicated in
96 * @result->t and any converted value is placed into an appropriate member of
97 * the union in @result.
98 *
99 * The function returns the parameter number if the parameter was matched,
100 * -ENOPARAM if it wasn't matched and @desc->ignore_unknown indicated that
101 * unknown parameters are okay and -EINVAL if there was a conversion issue or
102 * the parameter wasn't recognised and unknowns aren't okay.
103 */
104int __fs_parse(struct p_log *log,
105 const struct fs_parameter_spec *desc,
106 struct fs_parameter *param,
107 struct fs_parse_result *result)
108{
109 const struct fs_parameter_spec *p;
110
111 result->uint_64 = 0;
112
113 p = fs_lookup_key(desc, param, negated: &result->negated);
114 if (!p)
115 return -ENOPARAM;
116
117 if (p->flags & fs_param_deprecated)
118 warn_plog(log, "Deprecated parameter '%s'", param->key);
119
120 /* Try to turn the type we were given into the type desired by the
121 * parameter and give an error if we can't.
122 */
123 if (is_flag(p)) {
124 if (param->type != fs_value_is_flag)
125 return inval_plog(log, "Unexpected value for '%s'",
126 param->key);
127 result->boolean = !result->negated;
128 } else {
129 int ret = p->type(log, p, param, result);
130 if (ret)
131 return ret;
132 }
133 return p->opt;
134}
135EXPORT_SYMBOL(__fs_parse);
136
137/**
138 * fs_lookup_param - Look up a path referred to by a parameter
139 * @fc: The filesystem context to log errors through.
140 * @param: The parameter.
141 * @want_bdev: T if want a blockdev
142 * @flags: Pathwalk flags passed to filename_lookup()
143 * @_path: The result of the lookup
144 */
145int fs_lookup_param(struct fs_context *fc,
146 struct fs_parameter *param,
147 bool want_bdev,
148 unsigned int flags,
149 struct path *_path)
150{
151 struct filename *f;
152 bool put_f;
153 int ret;
154
155 switch (param->type) {
156 case fs_value_is_string:
157 f = getname_kernel(param->string);
158 if (IS_ERR(ptr: f))
159 return PTR_ERR(ptr: f);
160 param->dirfd = AT_FDCWD;
161 put_f = true;
162 break;
163 case fs_value_is_filename:
164 f = param->name;
165 put_f = false;
166 break;
167 default:
168 return invalf(fc, "%s: not usable as path", param->key);
169 }
170
171 ret = filename_lookup(dfd: param->dirfd, name: f, flags, path: _path, NULL);
172 if (ret < 0) {
173 errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
174 goto out;
175 }
176
177 if (want_bdev &&
178 !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) {
179 path_put(_path);
180 _path->dentry = NULL;
181 _path->mnt = NULL;
182 errorf(fc, "%s: Non-blockdev passed as '%s'",
183 param->key, f->name);
184 ret = -ENOTBLK;
185 }
186
187out:
188 if (put_f)
189 putname(name: f);
190 return ret;
191}
192EXPORT_SYMBOL(fs_lookup_param);
193
194static int fs_param_bad_value(struct p_log *log, struct fs_parameter *param)
195{
196 return inval_plog(log, "Bad value for '%s'", param->key);
197}
198
199int fs_param_is_bool(struct p_log *log, const struct fs_parameter_spec *p,
200 struct fs_parameter *param, struct fs_parse_result *result)
201{
202 int b;
203 if (param->type != fs_value_is_string)
204 return fs_param_bad_value(log, param);
205 if (!*param->string && (p->flags & fs_param_can_be_empty))
206 return 0;
207 b = lookup_constant(bool_names, param->string, -1);
208 if (b == -1)
209 return fs_param_bad_value(log, param);
210 result->boolean = b;
211 return 0;
212}
213EXPORT_SYMBOL(fs_param_is_bool);
214
215int fs_param_is_u32(struct p_log *log, const struct fs_parameter_spec *p,
216 struct fs_parameter *param, struct fs_parse_result *result)
217{
218 int base = (unsigned long)p->data;
219 if (param->type != fs_value_is_string)
220 return fs_param_bad_value(log, param);
221 if (!*param->string && (p->flags & fs_param_can_be_empty))
222 return 0;
223 if (kstrtouint(s: param->string, base, res: &result->uint_32) < 0)
224 return fs_param_bad_value(log, param);
225 return 0;
226}
227EXPORT_SYMBOL(fs_param_is_u32);
228
229int fs_param_is_s32(struct p_log *log, const struct fs_parameter_spec *p,
230 struct fs_parameter *param, struct fs_parse_result *result)
231{
232 if (param->type != fs_value_is_string)
233 return fs_param_bad_value(log, param);
234 if (!*param->string && (p->flags & fs_param_can_be_empty))
235 return 0;
236 if (kstrtoint(s: param->string, base: 0, res: &result->int_32) < 0)
237 return fs_param_bad_value(log, param);
238 return 0;
239}
240EXPORT_SYMBOL(fs_param_is_s32);
241
242int fs_param_is_u64(struct p_log *log, const struct fs_parameter_spec *p,
243 struct fs_parameter *param, struct fs_parse_result *result)
244{
245 if (param->type != fs_value_is_string)
246 return fs_param_bad_value(log, param);
247 if (!*param->string && (p->flags & fs_param_can_be_empty))
248 return 0;
249 if (kstrtoull(s: param->string, base: 0, res: &result->uint_64) < 0)
250 return fs_param_bad_value(log, param);
251 return 0;
252}
253EXPORT_SYMBOL(fs_param_is_u64);
254
255int fs_param_is_enum(struct p_log *log, const struct fs_parameter_spec *p,
256 struct fs_parameter *param, struct fs_parse_result *result)
257{
258 const struct constant_table *c;
259 if (param->type != fs_value_is_string)
260 return fs_param_bad_value(log, param);
261 if (!*param->string && (p->flags & fs_param_can_be_empty))
262 return 0;
263 c = __lookup_constant(tbl: p->data, name: param->string);
264 if (!c)
265 return fs_param_bad_value(log, param);
266 result->uint_32 = c->value;
267 return 0;
268}
269EXPORT_SYMBOL(fs_param_is_enum);
270
271int fs_param_is_string(struct p_log *log, const struct fs_parameter_spec *p,
272 struct fs_parameter *param, struct fs_parse_result *result)
273{
274 if (param->type != fs_value_is_string ||
275 (!*param->string && !(p->flags & fs_param_can_be_empty)))
276 return fs_param_bad_value(log, param);
277 return 0;
278}
279EXPORT_SYMBOL(fs_param_is_string);
280
281int fs_param_is_blob(struct p_log *log, const struct fs_parameter_spec *p,
282 struct fs_parameter *param, struct fs_parse_result *result)
283{
284 if (param->type != fs_value_is_blob)
285 return fs_param_bad_value(log, param);
286 return 0;
287}
288EXPORT_SYMBOL(fs_param_is_blob);
289
290int fs_param_is_fd(struct p_log *log, const struct fs_parameter_spec *p,
291 struct fs_parameter *param, struct fs_parse_result *result)
292{
293 switch (param->type) {
294 case fs_value_is_string:
295 if ((!*param->string && !(p->flags & fs_param_can_be_empty)) ||
296 kstrtouint(s: param->string, base: 0, res: &result->uint_32) < 0)
297 break;
298 if (result->uint_32 <= INT_MAX)
299 return 0;
300 break;
301 case fs_value_is_file:
302 result->uint_32 = param->dirfd;
303 if (result->uint_32 <= INT_MAX)
304 return 0;
305 break;
306 default:
307 break;
308 }
309 return fs_param_bad_value(log, param);
310}
311EXPORT_SYMBOL(fs_param_is_fd);
312
313int fs_param_is_file_or_string(struct p_log *log,
314 const struct fs_parameter_spec *p,
315 struct fs_parameter *param,
316 struct fs_parse_result *result)
317{
318 switch (param->type) {
319 case fs_value_is_string:
320 return fs_param_is_string(log, p, param, result);
321 case fs_value_is_file:
322 result->uint_32 = param->dirfd;
323 if (result->uint_32 <= INT_MAX)
324 return 0;
325 break;
326 default:
327 break;
328 }
329 return fs_param_bad_value(log, param);
330}
331EXPORT_SYMBOL(fs_param_is_file_or_string);
332
333int fs_param_is_uid(struct p_log *log, const struct fs_parameter_spec *p,
334 struct fs_parameter *param, struct fs_parse_result *result)
335{
336 kuid_t uid;
337
338 if (fs_param_is_u32(log, p, param, result) != 0)
339 return fs_param_bad_value(log, param);
340
341 uid = make_kuid(from: current_user_ns(), uid: result->uint_32);
342 if (!uid_valid(uid))
343 return inval_plog(log, "Invalid uid '%s'", param->string);
344
345 result->uid = uid;
346 return 0;
347}
348EXPORT_SYMBOL(fs_param_is_uid);
349
350int fs_param_is_gid(struct p_log *log, const struct fs_parameter_spec *p,
351 struct fs_parameter *param, struct fs_parse_result *result)
352{
353 kgid_t gid;
354
355 if (fs_param_is_u32(log, p, param, result) != 0)
356 return fs_param_bad_value(log, param);
357
358 gid = make_kgid(from: current_user_ns(), gid: result->uint_32);
359 if (!gid_valid(gid))
360 return inval_plog(log, "Invalid gid '%s'", param->string);
361
362 result->gid = gid;
363 return 0;
364}
365EXPORT_SYMBOL(fs_param_is_gid);
366
367int fs_param_is_blockdev(struct p_log *log, const struct fs_parameter_spec *p,
368 struct fs_parameter *param, struct fs_parse_result *result)
369{
370 return 0;
371}
372EXPORT_SYMBOL(fs_param_is_blockdev);
373
374int fs_param_is_path(struct p_log *log, const struct fs_parameter_spec *p,
375 struct fs_parameter *param, struct fs_parse_result *result)
376{
377 return 0;
378}
379EXPORT_SYMBOL(fs_param_is_path);
380
381#ifdef CONFIG_VALIDATE_FS_PARSER
382/**
383 * fs_validate_description - Validate a parameter specification array
384 * @name: Owner name of the parameter specification array
385 * @desc: The parameter specification array to validate.
386 */
387bool fs_validate_description(const char *name,
388 const struct fs_parameter_spec *desc)
389{
390 const struct fs_parameter_spec *param, *p2;
391 bool good = true;
392
393 for (param = desc; param->name; param++) {
394 /* Check for duplicate parameter names */
395 for (p2 = desc; p2 < param; p2++) {
396 if (strcmp(param->name, p2->name) == 0) {
397 if (is_flag(param) != is_flag(p2))
398 continue;
399 pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
400 name, param->name);
401 good = false;
402 }
403 }
404 }
405 return good;
406}
407#endif /* CONFIG_VALIDATE_FS_PARSER */
408